Mass effect means that something is pressing on the thecal sac (which is a thin walled tube filled with cerebrospinal fluid (CSF) that surrounds the spinal cord). Your MRI probably says something before this sentence like "causing mass effect ......." usually a bone spur, a bulged disc, can be other things but those are more rare.

knowing just exactly how this particular finding was worded upon the rad report would help in possibly giving you a better idea of what is actually 'causing' this mass effect to appear as it is. i know when they thought i had an AVM inside of my spinal cord it was worded that i appeared to have some type of vascular lesion that created a "mass effect" indicative of AVM. it was actually the veinous counterpart of AVM,a cavernous hemangioma. but you have a "something" there that is creating that mass effect to appear on your films. you just may need some better,more in depth testing to actually find out what it is. i needed to have an angiogram done on my cord area to find out whether it lit up and would be the original AVM,and if it did not light up,it would be veinous,which it was. have you consulted with a neurosurgeon yet at all?

if you could actually just type out your MRI summary that is located at the very end of your report,it would possibly help give us some insight here to work from. marcia